In recent years, there is a trend to assign a universal resource identifier (URI), which is a globally unique identifier, to each program broadcasted on television, and to provide a service in which an Internet service and a television broadcast program are linked by use of the URI. As a method of assigning a URI to each program broadcasted on television, there is a method of automatically generating a URI from service information (SI) included in a broadcast wave of a television broadcast. Note that in this method, a URI is an identifier dependent on the broadcaster or the like. As a result, a single program may be assigned different URIs depending on areas.
A social network service (SNS) can be considered as an example of an Internet service being linked with a program broadcasted on television by use of the URI assigned to the television program. In SNS, a plurality of users share a URI assigned to a program broadcasted on television. For example, when user A informs user B of a program user A is currently viewing, and concurrently informs user B of the URI of the program, user B is able to view the same program by using (such as simply clicking) the URI.
Such a service in which a URI for identifying a television program and an Internet service are linked, particularly a service in which a plurality of users share a URI, faces some problems. To be specific, television B of user B may not be able to process a URI generated by television A of user A. For example, in a case where television B accesses a URI after the passage of a certain time from the time when television A generates the URI, the program may already be ended. In this case, user B cannot view the program identified by the URI by just clicking the URI. Moreover, when televisions A and B belong to different broadcast areas, such as television A being located in Tokyo and television B being located in Osaka, television B cannot identify the program from the URI generated by television A. This is because the URI of the television program is determined depending on the broadcaster or the like of the television program.
The above mentioned technology is disclosed in M. McRobert, “Automatic Service Discovery with TVDNS,” [online], Jun. 12, 2010, Project Bird, [Searched on 14 Nov., 2011], the Internet <URL: http://projectbaird.com/discovery/tvdns/>, corresponding portion: TVDNS Specification, section (r02-2010-06-12), and contents of which are hereby incorporated by reference.